Fight the trainers in alleyways, get haircuts, participate in the battle restaurants, and do the part time jobs at the hotel. Also, talk to Alexa in the Lumiose Press building at least once. Repeat until they acknowledge you. That said, the clothes there are, like, 100k minimum in price, but there's allegedly a special item in the game that decreases the price. Nobody online seems to know where to find it, though, as of yet.

haha, honestly, no clue. I haven't really used my goomy yet, as adorable as he was. My Charizard and Raichu were almost all I needed for the E4. Not to mention, the dragon trainer, and a spattering of fairy pokemon, made a dragon type feel like a liability Still, if you need exp, and you're out of trainers, victory road might work, or you could possibly re-challenge the restaurants 'til you were all set.

If I could just offer one bit of advice, though, make sure you utilize Pokemon-Amie. Getting a high affection rate makes your pokemon way better.